In the prior art, injection drilling anchors are known from DE 34 00 182 C that can comprise a plurality of anchor rods connected by means of coupling nuts for achieving greater anchor lengths. With regard to known injection drilling anchors, reference is also made to DE 38 28 335 C1. Depending on the desired use, one speaks of injection drilling anchors, injection piles, micro piles, soil nails or rock anchors. For connecting individual anchor rods provided with an external thread (in many cases a continuous thread), different coupling sleeves or coupling nuts provided with a matching internal thread are known in the prior art. In the case of a simple construction, a central threadless portion is provided in the coupling sleeve, which prevents the anchor rods from being screwed through the coupling sleeve. The disadvantage of this is that the end of the thread at the center stop can be produced only with a conical run-out or with an undercut. In either case this has disadvantages for the rotary-percussive drilling of the injection drilling anchor that is desired in many applications, and also for a desired later backlash-free load transmission of alternating compressive and tensile forces. In the case of the rotary-percussive drilling of injection drilling anchors, in first instance, a drill bit is secured on a longitudinal end of an anchor rod (e.g., screwed on), it being optionally possible that for extension purposes, one or a plurality of anchor rods is/are already connected to the opposite longitudinal end by means of coupling nuts. A drive acts on the longitudinal end opposite to the drill bit, and the drive, in addition to a torque, also exerts percussive blows which act in a pulsating manner in the longitudinal and/or axial direction so as to facilitate penetrating through solid layers, for example in the bedrock. Depending on the number of anchor rods and the embodiment of the couplings, there is a risk that a portion of the impact energy gets lost between the drive and the drill bit. In a further known embodiment, the coupling sleeve has in its interior two thread ends that are offset with respect to one another by half a turn whereby, however, screwing-through of anchor rods can be prevented only up to a limited screw-in torque, and wherein here as well, the compression and impact transmission in the coupling sleeve via only the thread is perceived as being disadvantageous. Also, attempts have already been made to weld an inner stop for the anchor rods into the coupling sleeves or, for example, to insert for this purpose a spring pin into the thread. However, a limited compression transmission and an undesirable notch effect are again perceived as a disadvantage. A coupling sleeve provided with an internal thread for anchor rods of self-drilling injection anchors is also known from EP 0 391 119 B1. For cost-effective manufacturability it is provided that the cylindrical base area of the internal thread is followed by a conically extending base area on which the internal thread continues. Finally, from DE 42 20 636 B4, a coupling sleeve of the aforementioned kind is known, wherein for achieving a reliable tightness, it is proposed that an axial end stop for an end face of a screwed-in injection anchor rod is formed in the coupling sleeve, that a separate sealing element in the form of an O-ring that leaves a central opening is accommodated upstream of this end stop, that the sealing element is disposed in a circumferential radial recess that intersects the course of the thread, and that the recess in terms of its depth corresponds approximately to the depth of the thread root of the internal thread. Although this connecting element has advantages over the previously mentioned coupling nuts with regard to the tightness, there appears to be the limitation that the O-rings are located in the flow of forces and, in particular in the case of axial alternating load, can result in slip, leading to power loss.